Showing 11 results for Zakerzadeh
Hamid Basaeri, Mohammad Reza Zakerzadeh, Aghil Yousefi Koma, Seyed Saeid Mohtasebi,
Volume 15, Issue 5 (7-2015)
Abstract
The scope of the current investigation incorporates the entire process involved in design and development of a Shape Memory Alloy (SMA) actuated wing intended to fulfill morphing missions. At the design step, a two Degree-of-Freedom (DOF) mechanism is designed that is appropriate for morphing wing applications. The mechanism is developed in such a way that it can undergo different two DOF, i.e. gull and sweep, so that the wing can have maneuvers that are more efficient. Smart materials commonly are selected as the actuators due to their suitable thermo-mechanical characteristics. Shape Memory Alloy (SMA) actuators are capable of providing more efficient mechanisms in comparison to the conventional actuators due to their large force/stroke generation, smaller size with high capabilities in limited spaces, and lower weight. As SMA wires have nonlinear hysteresis behavior, their modeling should be implemented in a meticulous way. In this work, after proposing a two DOF morphing wing, an aerodynamic analysis of the whole wing for unmorphed and morphed wings is presented. The results show that the performance of the morphed wing in special flight regimes is improved.
Ali Reza Rarivar, Mohammad Reza Zakerzadeh,
Volume 15, Issue 7 (9-2015)
Abstract
The purpose of this paper is design, construction and the control of a two-wheel self-balancing robot. For this purpose firstly, a literature study is carried out on the history of manufactured self-balancing robots and the researches which have been done so far in this area are reported. In addition, the robot chassis with consideration of the size and material is analyzed; and the dynamic equations of the robot are computed according to the designed chassis. Then, the robot inertial parameters are measured through different experimental tests and these parameters are used in the equations. Also, the derived equations are simplified and the transfer functions are evaluated for considering the stability of the robot. In this self-balancing robot, the simplified Kalman and complementary filters are used for identifying of the bias angle from the vertical position by combination of data obtained from accelerometer and gyroscope sensors. The PID controller and the robot transfer functions are simulated in MATLAB software. Then, the controller gains are obtained for the stability of the constructed robot. These gains are computed by PID tuning toolbox of MATLAB software as well as theoretically, and the results in each method have been compared with each other. Finally, the robot control electronic circuit is designed for analyzing the results through AVR microcontroller, while angle identification sensor is used.
Osve Jaddinia, Mohammad Reza Zakerzadeh, Mohammad Mahjoob,
Volume 15, Issue 11 (1-2016)
Abstract
Today, due to ever-increasing demand for fast and precise movements and changes, along with small-scale actuations in many engineering fields, the use and efficiency of smart materials has increased in importance. Magnetic Shape Memory Alloy (MSMA) is one of the latest smart materials having both shape memory and magnetic properties. As a matter of fact, in normal room temperatures, it has magnetic field-induced strains far more than any other smart materials such as magnetostrictive, piezoelectric or electrostrictive materials and its frequency response is greater than thermal shape memory alloy. However, on the downside, asymmetric hysteresis is a property that constrains its widespread applications. Prandtl-Ishlinskii model is one of the powerful phenomenological models for simulating asymmetric, non-linear hysteresis used to simulate smart material behavior. In the present study, MSMA hysteresis behavior simulation has been investigated through a new approach using generalized Prandtl-Ishlinskii model. After identifying the model parameters, the study compares the predicted output with the experimental results. For validation the model, using different data, model accuracy has been checked and prediction error has been compared. The experimental results have approved the capability of the model in predicting the hysteresis behavior. Thanks to invertible and simplicity potential of the generalized Prandtl-Ishlinskii model, the inverse of model can be applied as a feedforward controller for compensating the hysteresis behavior. It should also be noted that all the experimental results have been yielded through using experimental set-up.
Mohammad Reza Zakerzadeh, Hamid Salehi, Abolfazl Salehi, Mostafa Baghani,
Volume 16, Issue 2 (4-2016)
Abstract
In this paper, an innovative flexible sandwich structure is introduced which can be used in shape changing (morphing) aircrafts that adapt their external shape to different flight conditions. First, different ideas for achieving smart aircraft in the literature is briefly reviewed and then characteristics of the new deformable sandwich structure as well as its different features in comparison to other proposed structures are described. Moreover, fabrication details of deformable and load bearable sandwich panel are explained. In an aircraft with variable camber wings, deformable sections can be supposed as a cantilever beam. As a result some specimens of new deformable sandwich structure are constructed and then tested as end-loaded beams. Since the numerical study of the new proposed structure requires an understanding of the mechanical behavior of components used, a comprehensive study about the mechanical behavior of individual components of structure is conducted. According to the observation of broken samples, a distribution of cavities resulting from the manufacturing process is supposed in one type of model to obtain more accurate numerical results. Finally, another example is analyzed with the same assumptions and it is shown that in the second example, the numerical results are close to the experimental data.
Saeid Shakki, Mohammad Reza Zakerzadeh,
Volume 16, Issue 7 (9-2016)
Abstract
Shape memory alloys (SMAs) are suitable candidates in various fields of engineering. One advantage of these alloys is their capabilities in developing high strain and force. In addition to these great features, lightweight and super-elastic behavior are other traits of these materials. These specifications are of such an importance that make SMAs to be suitably used in further engineering applications. However, their intrinsic hysteresis non-linear behavior make their usage as position actuators difficult. Despite this challenge, there are various methods proposed in the literatures to model the hysteresis behavior of such materials. In this paper, a generalized Prandtl- Ishlinskii model, because of its simplicity, efficiency and inverse analytical capability, has been used for modeling the SMA behavior. In addition, the hysteresis modeling has been validated via experimental data of one of the articles. In the control section, however, two control systems consisting PID and fuzzy sliding mode controllers have been used. Fuzzy sliding mode control system is a method that can be used in systems without mathematical model and leads to increase in their robustness. It is shown in this paper that by using this method, it is possible to apply a suitable control input to the system in order to vanish the error signal. However, by using PID controllers, the error signal is not acceptable due to the constant controller coefficients. The results indicate the more efficient performance of fuzzy sliding mode controller with respect to the classical PID controller.
Saeid Shakki, Mohammad Reza Zakerzadeh, Moosa Ayati, Osve Jeddinia,
Volume 16, Issue 11 (1-2017)
Abstract
The hysteresis nonlinearity of the Magnetic Shape Memory Alloy (MSMA) actuator limits its control applications. To tackle the problems, usually the hysteresis behavior of these materials is models. Prandtl-Ishlinskii (PI) model is more practical in this area, because of its simplicity and having analytical inverse. Two versions of this model, entitled: rate-independent model and rate-dependent model, have been developed. Experimental results show that with increasing input frequency, the shape of hysteresis loops is amplified. In this study, by using experimental test setup the input voltage is applied to the MSMA actuator at the frequencies 0.05- 0.4 Hz and the displacement output captured by proximity position sensor, also the MSMA is modeled by generalized rate-dependent Prandtl-Ishlinskii (GRDPI) model and modified generalized rate-dependent Prandtl-Ishlinskii (MGRDPI) model. The modified version of the model are presented by the authors to enhance the ability of the GRDPI model for describing the asymmetric and saturated hysteresis behavior in MSMAs by hyperbolic tangent function in the model output. For training of the mentioned models, the actuation frequencies 0.05 and 0.2 Hz are selected and the model parameters of each model are also obtained by using genetic algorithm (GA). For validation of the models the hysteresis loop at frequency 0.1, 0.3 and 0.4 Hz is selected. The result shows that, due to using hyperbolic tangent function in the model output, the modified version of the GRDPI model can describe the hysteresis behavior in MSMAs more accurately.
Farshid Sadeghian, Morad Karimpour, Mohammad Reza Zakerzadeh, Mostafa Baghani,
Volume 17, Issue 10 (1-2018)
Abstract
Many people suffering from neuromuscular diseases, have some degree of limitations in their walking pattern. Knee-Ankle-Foot Orthoses (KAFOs) help correct patients’ gait pattern by supporting knee and ankle joints. Patients with quadriceps muscle weakness suffer from some restrictions in extension as well as in controlling their flexion during the gait cycle because of abnormal stiffness pattern of the knee joint. This paper addresses patients with quadriceps muscle weakness by designing an appropriate orthosis utilizing two different mechanisms for the stance and swing phases. Stance phase mechanism locks knee joint movement from the initial-contact up to the end of mid-swing phase and with regards to the orientation of the foot after mid-stance phase, the knee joint can flex freely. The required moment to reproduce the stiffness of a normal knee joint is calculated using the OpenSim software package in conjunction with the data collected from the motion analysis of each patient.
The required moment to modify the stiffness of the knee joint for two patients with different levels of muscle weakness was reproduced using a torsional spring. By designing patient-specific orthosis, the stiffness profile of normal joint for each patient with distinct level of muscle weakness can be reproduced, allowing patients to experience smother gait cycle. Using this orthosis not only improves the patient’s gait cycle but also prevents potential damage to healthy muscles.
Pouya Fahimi, Mostafa Baghani, Mohammad Reza Zakerzadeh,
Volume 17, Issue 12 (2-2018)
Abstract
In this work, torsional modeling and experimental characterization of a Shape Memory Alloy (SMA) rod is investigated. Experimental tests of previous studies proved that different direction of loading is effective on torque-angle response of a rod. Accordingly, using improved Brinson’s model and converting it to a torsional model and referring a twist deformation in the clockwise direction to a positive twist and a twist deformation in the counter clockwise direction to a negative twist, the asymmetry effect on the rod is investigated. Assuming a linear strain through the cross section and then finding stresses, using the asymmetric Brinson model, and integrating the stresses through the cross section the torque-angle response of the rod is presented, by using a numerical procedure. The parameters for Brinson model, including phase transformation temperatures, are derived from experimental tests and there is more than 95% agreement between the present model and experimental test. Regarding the results, a verification for the derived parameters is presented and a parametric study on SMA rod is considered. The average error of asymmetric and symmetric models with respect to the experimental tests are 5% and 15% respectively. Moreover, hysteresis inner loops are studied and asymmetric model is compared to the experimental tests. The results show good agreement of the asymmetric model when compared to experimental tests.
Samira Akbari-Azar, Mostafa Baghani, Hamid Shahsavari, Mohammad Reza Zakerzadeh, Saeed Sohrabpour,
Volume 18, Issue 1 (3-2018)
Abstract
In this paper, a sandwich beam of a SMP material which have a corrugated core is studied. The corrugated core is from a polymeric material. Structures with corrugated profiles show higher stiffness-to-mass ratio in the transverse to corrugation direction compared to flat structures. As a result, the beam with corrugation along the transverse direction is stiffer than the one with corrugation along the beam length. The flexural behavior of the composite corrugated beam is studied employing a developed constitutive model for SMP and the Euler-Bernoulli beam theory. The constitutive model utilized is in integral form and is discretized employing finite difference scheme. To verify the results of the Euler-Bernoulli beam theory and finite difference method, finite element models of different corrugated sections have been simulated in a 3D finite element program. The results demonstrate that the developed model for the composite beam presented in this study predicts the behavior of the beam successfully. The sandwich beam with different corrugated cores (triangular, sinusoidal and trapezoidal shapes) are compared with each other. Also, results show that the shape fixity is decreased a little, like any other reinforcing method. This decrease in shape fixity results in increase of load capacity in composite beams. The stress-free strain recovery and constrained stress-recovery cycles are both studied.
Mohsen Soltani, S. Mohammad Bozorg, Mohammad Reza Zakerzadeh,
Volume 18, Issue 1 (3-2018)
Abstract
In order to use and control Shape Memory Alloy (SMA) actuators, it is essential to measure its state variables to be used as the feedback in the control loop. The wire temperature is one of critical state variables need to be fed back. However, measuring this variable is difficult and usually contains some noises and delay. Therefore, it is desirable to estimate this variable instead of measuring it. Thermoelectric model is one of the most common models used to estimate the SMA wire temperature. This model calculates the SMA wire temperature based on its input electric current. In this paper, first three unknown parameters of thermoelectric model are estimated using Extended Kalman filter (EKF) and the wire temperature is calculated based on the identified model. The parameter estimation and temperature calculation are performed on a practical SMA actuator. Then, in order to eliminate the effects of environmental disturbances and the thermoelectric model inaccuracies, the temperature is estimated using EKF. In this method, all measurable data such as the input current, the strain and stress of the SMA wire are used in the temperature estimation. The estimator combines the information obtained from both thermoelectric and Brinson models and the measurement data. This method is used for online temperature estimation of the SMA wire on a practical SMA actuator. The results show that the estimated temperature matches the actual wire temperature with high precision. Furthermore, the temperature estimation using EKF is more accurate than the estimates of the thermoelectric model.
Sh. Yahyaei, M. Zakerzadeh , A. Bahrami ,
Volume 19, Issue 1 (January 2019)
Abstract
The dynamic response of shape memory alloy (SMA) systems and structures often exhibits a complex behavior due to their intrinsic nonlinear characteristics. The key characteristics of SMAs stem from adaptive dissipation associated with the hysteretic loop and huge changes in mechanical properties caused by the martensitic phase transformation. These exceptional properties have attracted attention of many researchers in various engineering fields from biomedicine to aerospace. One of the possible responses that may happen in SMA structures is the chaotic response, which can lead to a massive change in the system behavior. Moreover, such a system is highly sensitive to initial conditions. Therefore, its analysis is essential for a proper design of SMA structures. The present article discusses nonlinear dynamics and chaotic behavior in a one-degree-of-freedom (1DoF) oscillator connected to SMA at constant working temperature and pseudo elastic region. Equation of motion is formulated, using the Brinson constitutive model. Combination of structural equations of SMA and dynamical and kinematic relations, as well as forth-order Runge-Kutta scheme are employed to solve the equation governing the oscillator motion. Free and forced vibrations under the influence of harmonic stimulation force and in a wide range of excitation frequencies are presented in the form of various numerical examples. Different tools for detecting chaos, including, phase plane, time response, frequency response, Lyapunov exponent, and Poincare map are used to determine the type of motion. Numerical simulations demonstrate a wide range of periodic, quasi periodic, and chaotic responses for certain values of excitation frequencies, which is a reason for the proper understanding of the behavior of these systems.
